1. Field of the Invention
The present invention relates generally to an electrical terminal having insulation piercing connection technology. More specifically, the present invention is directed to an electrical terminal for locking onto a mounting rail.
2. Description of Related Art
Electrical terminals, especially terminal blocks, have been known for decades and millions are used in the wiring of electrical systems and devices. The terminals are generally locked onto mounting rails which, for their part, are often located in a switchgear cabinet. The terminals are generally made as connecting terminals in that they have at least two conductor terminal elements which are electrically connected to one another via an electrically conducting connecting bar (i.e., a busbar). In addition to this basic type of terminal block, there are a host of different types of terminal blocks which are specially adapted based on each respective application for which the terminal block is used. For example, there are two-tier or three-tier terminals and three-conductor or four-conductor terminals which then each have a correspondingly larger number of conductor terminal elements.
In terminal blocks the conductor terminal elements are mainly screw terminals or tension spring terminals. The clamping principle in tension spring terminals is similar to that of screw technology. While in a screw terminal a tension sleeve pulls the conductor against the busbar by actuation of the terminal screw, in a tension spring terminal this task is assumed by the tension spring. To do this, the pretensioned tension spring is opened with an actuation tool (e.g., a screwdriver) so that the conductor can be inserted through a window in the leg of the tension spring into the connection space. After removing the actuating tool the conductor is pulled against the busbar by the spring force of the tension spring.
Both in the screw terminal and in the tension spring terminal, the electrical conductor must first be stripped after being cut to length, before contact-making of the electrical conductor can take place. Since special tools are required for stripping the electrical conductor, and since stripping takes a relatively large amount of time, for many years electrical terminals have been used, to which electrical conductors can be connected without prior stripping. To do this, the insulated conductor is inserted into a conductor receiver in the housing of the terminal and then pressed into an insulation piercing element, by which the insulation of the conductor is pierced and the core of the conductor makes contact with the insulation piercing element. In this regard, there are a host of possible embodiments of these terminals for connection of unstripped conductors. They differ especially in how the conductor, which has been inserted into the conductor receiver, is pressed into the insulation piercing element.
The initially described electrical terminal in insulation piercing technology is known, for example, from published German Patent Application DE 199 21 775 A1. In this known connecting terminal, the actuating elements are supported by means of relatively large, wheel-like guides in a rotary support which is formed by the side wall of the housing. Because the actuating elements are pivotally supported directly in the side wall of the housing, a maximum diameter is available for a conductor which is to be connected. Thus, for a given conductor cross section, the width of the electrical terminal can be chosen to be relatively small. The wheel-like guide of the actuating elements in the side wall however has the disadvantage that, as a result of the large wheel-like guides, the height of the electrical terminal is also relatively great. Moreover, due to the large, wheel-like guides, under certain circumstances, problems can arise in the adherence to the required creepage distances, Thus, insulation problems arise especially for higher currents.